Treat $x/ or $(x)/ as ./ when finding sourced files (fixes #1998)

CHANGELOG.md

@@ -8,6 +8,9 @@
 - SC1072/SC1073 now respond to disable annotations, though ignoring parse errors
   is still purely cosmetic and does not allow ShellCheck to continue.
 
+### Changed
+- SC1090: A leading `$x/` or `$(x)/` is now treated as `./` when locating files
+
 
 ## v0.7.1 - 2020-04-04
 ### Fixed

src/ShellCheck/ASTLib.hs

@@ -503,6 +503,11 @@ isCommandSubstitution t = case t of
     T_Backticked {} -> True
     _ -> False
 
+-- Is this an expansion that results in a simple string?
+isStringExpansion t = isCommandSubstitution t || case t of
+    T_DollarArithmetic {} -> True
+    T_DollarBraced {} -> not (isArrayExpansion t)
+    _ -> False
 
 -- Is this a T_Annotation that ignores a specific code?
 isAnnotationIgnoringCode code t =

src/ShellCheck/Checker.hs

@@ -229,6 +229,12 @@ prop_cantSourceDynamic =
 prop_cantSourceDynamic2 =
     [1090] == checkWithIncludes [("lib", "")] "source ~/foo"
 
+prop_canStripPrefixAndSource =
+    null $ checkWithIncludes [("./lib", "")] "source \"$MYDIR/lib\""
+
+prop_canStripPrefixAndSource2 =
+    null $ checkWithIncludes [("./utils.sh", "")] "source \"$(dirname \"${BASH_SOURCE[0]}\")/utils.sh\""
+
 prop_canSourceDynamicWhenRedirected =
     null $ checkWithIncludes [("lib", "")] "#shellcheck source=lib\n. \"$1\""
 

src/ShellCheck/Parser.hs

@@ -2122,7 +2122,7 @@ readSource t@(T_Redirecting _ _ (T_SimpleCommand cmdId _ (cmd:file':rest'))) = d
     let file = getFile file' rest'
     override <- getSourceOverride
     let literalFile = do
-        name <- override `mplus` getLiteralString file
+        name <- override `mplus` getLiteralString file `mplus` stripDynamicPrefix file
         -- Hack to avoid 'source ~/foo' trying to read from literal tilde
         guard . not $ "~/" `isPrefixOf` name
         return name
@@ -2182,6 +2182,16 @@ readSource t@(T_Redirecting _ _ (T_SimpleCommand cmdId _ (cmd:file':rest'))) = d
             SourcePath x -> Just x
             _ -> Nothing
 
+    -- If the word has a single expansion as the directory, try stripping it
+    -- This affects `$foo/bar` but not `${foo}-dir/bar` or `/foo/$file`
+    stripDynamicPrefix word =
+        case getWordParts word of
+            exp : rest | isStringExpansion exp -> do
+                str <- getLiteralString (T_NormalWord (Id 0) rest)
+                guard $ "/" `isPrefixOf` str
+                return $ "." ++ str
+            _ -> Nothing
+
     subRead name script =
         withContext (ContextSource name) $
             inSeparateContext $